Daily cover is placed over the entire working face at the end of each working day. Typically, daily cover is soil but other alternative daily covers (ADC) may be approved. ADC's are defined in the site's SOP. In Covel Gardens' case, approved ADC's are synthetic material tarps, shredded brush materials, commercial spray-on foam products, dried water treatment screenings, construction and demolition debris and petroleum contaminated soils. The majority of daily cover applied at Covel Gardens is soil from excavations and stockpiles on the site. Tarps are used occasionally as well. When soil is used it is placed at a thickness of 6 inches.
Intermediate cover must be placed on areas that have received waste but will be inactive for a period longer than 180 days. Intermediate cover must be at least 12 inches in thickness.
Final Cover is placed over areas of the landfill that have reached full capacity and final design waste grades. The final cover system typically consists of multiple layers of materials. A re-compacted clay layer, followed by a synthetic liner, a drainage layer and topsoil represents a common Subtitle D final cover design. Alternative final cover systems may be approved by TCEQ. Some areas of Covel Gardens have been approved for an alternative final cover system that eliminates the synthetic liner.
